DE10228572B4 - Pure optical OR gate performed using optical semiconductor amplifier - Google Patents

Abstract

Device for purely optical OR logic operations with:
an optical pulse generator;
a mode-locked fiber laser (MLFL) for generating input signal patterns A and B for purely optical OR logic operations from the pulse generator;
a first fiber coupler (FC1) for branching the output from the mode-locked fiber laser through a 50:50 branch ratio;
a first optical delay means for delaying the optical output from the first fiber coupler;
a first optical control means for controlling the intensity and the polarization of the optical output from the first fiber coupler;
a second fiber coupler (FC2) for generating the input signal pattern A by coupling optical outputs from the first delay means and the first optical control means;
a third fiber coupler (FC3) for branching the optical output from the second fiber coupler through a branch ratio of 10:90;
second delay means for delaying the optical output from the second fiber coupler (FC2);
a fourth fiber coupler (FC4) for detecting the optical output from the second ...

Description

BACKGROUND THE INVENTION

Field of the invention

The The present invention relates to a purely optical OR gate under Use of gain saturation and wavelength conversion characteristics of semiconductor optical amplifiers (SOA). In particular, the present invention relates to a technique purely optical OR gate perform, which is purely optical Logical operations performed by the use of optical signals, which from arbitrary points of optical circuits, such as optical computing circuits, as a pump signal and a transmitter signal are transmitted.

description of related areas

In In recent years there has been a demand for high speed optical systems and a big one capacity increased dramatically. As the information networks of the future for multimedia services, like speech signals, stationary Pictures and moving pictures have to be prepared, it is expected that the information processing capacity of basic networks increases from a few hundred Gbit / s to a few Tbit / s. That's why purely optical signal processing techniques as core technologies come up to big data capacity to transfer, too process and exchange.

Especially, because purely optical logic operations avoid the cumbersome electro-optical conversion can, will it as a core technology for pure considered optical signal processing systems. That's why technologies are used of purely optical logic gates, in the field of optical computing and the purely optical signal processing developed.

To now have purely optical logic gates for an ultra-high speed optical Information processing mainly the non-linear characteristics of semiconductor optical amplifiers (SOAs) used. For example, purely optical logic gates are based on mechanisms like four-wave mixing (FWM), cross-enhancement modulation (XGM), Cross Phase Modulation (XPM), Cross Absorption Modulation (XAM) or Combinations of these.

Therefore were purely optical OR gates according to the prior art by Method realizes which ultrafast, non-linear interferometer (UNI) employing non-linear gain and refractive index change of semiconductor optical amplifiers (SOA) [See N.S. Patel, K.L. Hall and K.A. Rauschenbach, Opt. Lett. Issue 21, 1466 (1996)] and integrated SOA-based Michelson Interferometer [See T. Fjelde, D. Wolfson, A. Kloch, C. Janz, A. Coquelin, I. Guillemot, F. Gaborit, F. Poingt, B. Dagens and M. Renaud, Electronic Letters, Issue 36, 813 (2000)].

Around however, a variety of purely optical logic gates, such as AND, NAND, OR, NOR and XOR, in complicated optical circuits optical Use computational or purely optical signal processing systems to be able to it is desirable each of the purely optical logic gates to perform so that they on the same operating principle for one favorable System composition executed become. By using the gain saturation and the wavelength conversion characteristics of SOAs can purely optical NOR, XOR and NAND as well as purely optical OR or OR gates according to the present Invention executed become. [For pure NOR optical gates, see Y.T. Byun, S.H. Kim, D.H. Woo, D. H. Kim and S.H. Kim, New Physics, Issue 40, 560 (2000).]

SUMMARY THE INVENTION

The present invention solves the above-mentioned problems of the prior art. It is one Object of the present invention, a device designed for purely optical OR gates through the use of the characteristics of the gain saturation and the wavelength conversion of semiconductor optical amplifiers (SOAs).

Around to solve the above problem The present invention provides a purely optical OR logic device in which 2.5 Gbit / s input signals through four logic signals generates mode-locked fiber lasers and multiplexing, and then these logic signals and the encoder signal under the influence of the gain saturation and the wavelength conversion characteristics are while they are transmitted through the semiconductor optical amplifier (SOA).

The above and other features and advantages of the present Invention will become more readily apparent to those skilled in the art from the following detailed Description in conjunction with the accompanying drawings, which form part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

1 illustrates an arrangement diagram which ge a purely optical OR gate according to the present invention.

2 Fig. 10 shows waveforms of the signals A and B for a purely optical OR gate according to the present invention and the sum A + B of the two input signals.

3 Fig. 15 shows waveforms of the signals A and B for all-optical OR gates according to the present invention and the wavelength-converted signal.

4 illustrates the characteristics of a purely optical OR gate operated at 2.5 Gbit / s according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

in the Below is the composition and operation of the present Invention detailed by preferred embodiments with reference to the accompanying drawings.

1 illustrates the arrangement diagram of a device which performs a purely optical OR gate according to the present invention. 2 shows waveforms of signals A and B for the all-optical OR gate and the sum of the two input signals A + B. 3 FIG. 15 shows waveforms of the signals A and B of the all-optical OR gate and the wavelength-converted signal. 4 illustrates the characteristics of the purely optical OR gate operated at 2.5 Gbit / s.

An embodiment, such as in 1 shown, according to the present invention comprises an optical pulse generator ( 100 ), a mode-locked fiber laser (MLFL; 102 ) for generating input signal patterns A and B for a purely optical OR gate from the pulse generator ( 100 ), a first fiber coupler (FC1; 106 ) for branching the output from the mode locked fiber laser ( 102 ) by an isolator (ISO; 104 ) by a branch ratio of 50:50, a first optical delay means for delaying the output from the first fiber coupler (Fig. 106 ) by using a variable delay ( 108 ) and a single-mode fiber ( 110 ), a first optical control device for controlling the intensity and the polarization of the optical output from the first fiber coupler (US Pat. 106 ) by the use of a damper (ATTN; 112 ) and a polarization controller (PC; 114 ), a second fiber coupler (FC2; 116 ) for generating the input signal pattern A (1100) by coupling optical outputs from the first delay means and the first optical control means, a third fiber coupler (FC3; 118 ) for branching the optical output from the second fiber coupler (FC2; 116 ) by a branch ratio of 10:90, a second delay means for delaying the optical output from the second fiber coupler (US Pat. 116 ) by inserting a variable delay ( 120 ) and a single-mode fiber (SMF; 122 ), a fourth fiber coupler (FC4; 124 ) for detecting the input signal pattern B (0110) which is generated by the second delay means, a second optical control means for controlling the intensity and the polarization of the optical output from the third fiber coupler (US Pat. 118 ) by the use of a damper (ATTN; 126 ) and a polarization controller (PC; 128 ), a fifth fiber coupler (FC5; 130 ) for generating the input signal pattern A + B by coupling the input signal pattern A from the third Fa serkoppler ( 118 ) and the input signal pattern B from the fourth fiber coupler ( 124 ) and means for detecting and measuring the input signal pattern A + B received from the fifth fiber coupler ( 130 ) is produced.

The embodiment may additionally comprise a first Erbium doped fiber amplifier (EDFA1; 132 ) for amplifying the input signal pattern A + B received from the fifth fiber coupler ( 130 ), a wavelength-adjustable laser diode (adjustable LD; 134 ) to function as the light signal of the encoder signal of a continuous wave transmitted by the polarization controller (PC; 136 ), a sixth fiber coupler (FC6; 138 ) for coupling the input signal pattern A + B for the first erbium-doped fiber amplifier ( 132 ) and the encoder signal with a continuous wave from the adjustable laser diode ( 134 ) by a coupling ratio of 50:50, a first semiconductor optical amplifier (SOA1; 140 ) for generating the wavelength-converted signal pattern C by the SOA characteristics of the gain saturation and the wavelength conversion of the input signal pattern A + B received from the sixth fiber coupler (FIG. 138 ) is input simultaneously with the encoder signal, and a first optical filter ( 142 ) for filtering only the encoder signal from the first semiconductor optical amplifier ( 140 ) exhibit.

The embodiment may additionally include a second erbium doped fiber amplifier (EDFA2; 144 ) for amplifying the wavelength-converted signal pattern C from the first semiconductor optical amplifier ( 140 ), a distributed feedback laser diode (DFB-LD; 146 ) for generating continuous wave optical signals by a polarization controller (PC; 148 ), a seventh fiber coupler (FC7; 150 ) for coupling the signal pattern C, which in the second Erbi um-doped fiber amplifier ( 144 ) and the continuous wave optical signal from the laser diode ( 146 ) with distributed feedback through a 50:50 coupling rate, a second semiconductor optical amplifier (SOA2; 152 ) for generating a new wavelength-converted signal pattern by the SOA characteristics of the gain saturation and wavelength conversion from the input signal pattern C which functions as the pump signal and from the seventh fiber coupler (FIG. 150 ) is input simultaneously with the continuous wave optical signal as the encoder signal, a second optical filter (FIG. 154 ) for filtering only the encoder signal from the second semiconductor optical amplifier ( 152 ), a photodetector (PD; 156 ) for detecting the optical output from the second optical filter (Fig. 154 ) and a sampling oscilloscope ( 158 ) for measuring the detected optical output from the photodetector ( 156 ) exhibit.

Now, the execution process of a purely optical OR logic device according to the present invention will be described with reference to FIGS 2 . 3 and 4 described.

First, the input signal patterns A and B for verifying the all-optical OR logic operation by a mode-locked fiber laser (MLFL; 102 ), which has a wavelength of 1550 nm. The optical output of the mode-locked fiber laser ( 102 ) is detected by the first fiber coupler (FC1; 106 ), which has a branch ratio of 50:50, and then by the variable delay (FIG. 108 ) and a 4 m single-mode fiber ( 110 ) as a delay means for obtaining a time delay of 400 ps and through the damper (ATTN; 112 ) and the polarization controller (PC; 114 ) as a control device. passed through and then at the second fiber coupler (FC2; 116 ) having a 50:50 branch ratio to produce the input signal pattern A (1100) running at 2.5 Gbit / s.

Now, the upper fiber of the output end of the second fiber coupler ( 116 ) at the third fiber coupler (FC3; 118 ), which has a branch ratio of 10:90, and then the optical output ( 1100 ) of the upper fiber with a 20 GHz oscilloscope. The optical output ( 1100 ) of the deeper fiber is controlled by the damper (ATTN; 126 ) and the polarization controller (PC; 128 ) and then connected to the input signal pattern B (0110) at the fifth fiber coupler (FC5; 130 ) coupled.

On the other hand, the input signal pattern A (1100) is received from the lower fiber of the output end of the second fiber coupler (FC2; 116 ) by the variable delay ( 120 ) and a 4 m single-mode fiber (SMF; 122 ) to achieve a time delay of 400 ps, and then the input signal pattern B (0110) is generated. This signal is taken from the fourth fiber coupler (FC4; 124 ), which has a branch ratio of 10:90, and then the optical output ( 0110 ) of the upper fiber at a 45 GHz photodetector and a sampling oscilloscope. And the optical output of the lower fiber is connected to the input signal pattern A (1100) at the fifth fiber coupler (FC5; 130 ) coupled. The optical output from the upper fiber of the output end of the fifth fiber coupler (FC5; 130 ), which is the sum of the input signal patterns A and B, ie A + B, is measured by another 45 GHz photodetector and the sampling oscilloscope.

2 shows the input signal pattern A (1100) of 2.5 Gbit / s which is received from the upper fiber of the output end of the third fiber coupler (FC3; 118 ), the input signal pattern B (0110) of 2.5 Gbit / s, which is from the upper fiber of the output end of the fourth fiber coupler (FC4; 124 ), and also the input signal pattern A + B of 2.5 Gbit / s which is received from the upper fiber of the output end of the fifth fiber coupler (FC5; 130 ) is measured.

Now, the output pattern A + B from the lower fiber of the output end of the fifth fiber coupler (FC5; 130 ) in the first erbium-doped fiber amplifier (EDFA1; 132 ) at the sixth fiber coupler (FC6; 138 ) having a 50:50 branching ratio with a continuous wave optical signal from the tunable laser diode at a wavelength of 1535 nm, and is then coupled to the first semiconductor optical amplifier (SOA1; 140 ).

At this stage, the signal pattern C generated due to the gain saturation and the wavelength conversion characteristics of the first semiconductor optical amplifier (SOA1; 140 ) Is wavelength-converted. In other words, since the encoder signal is obtained from the output signal from the first optical amplifier (SOA1; 140 ) through the first optical filter ( 142 ), but the input signal pattern A + B does not pass, the wavelength-converted signal pattern C has the wavelength of 1535 nm.

3 shows the input signal patterns A and B of 2.5 Gbit / s and also the wavelength-converted signal pattern C of 2.5 Gbit / s, which at the output end of the first optical filter (FIG. 142 ) is measured when the driving currents for the first erbium-doped fiber amplifier (EDFA1; 132 ) and the first optical semiconductor amplifier (SOA1; 140 ) are each 80 mA and 150 mA. When two logic signals from the input signal pattern A and B are (1,0), (1,1) or (0,1), the wavelength-converted signal pattern C has no optical output although the optical output in the case of (FIG. 0.0) is present. However, since the input signal is of the pulse type, it is shown that the wavelength converted output signal occurs between optical pulses.

Now, the wavelength-converted signal pattern C in the second erbium-doped fiber amplifier (EDFA2; 144 ) at the seventh fiber coupler (FC7; 150 ) having a 50:50 branch ratio with the encoder signal of wavelength 1554 nm, which is distributed by the distributed feedback laser diode (DFB-LD; 146 ), and then the second semiconductor optical amplifier (SOA2; 152 ). At this stage, the wavelength-converted input signal C as the pump signal for the second semiconductor optical amplifier (SOA2; 152 ) while the continuous wave optical signal from the laser diode (DFB-LD; 146 ) is used with distributed feedback as the encoder signal. The high-intensity pump signal is gain-saturated by depleting the carrier concentration in the second semiconductor optical amplifier (SOA2; 152 ). As a result, the encoder signal has the output from the second semiconductor optical amplifier (SOA2; 152 ) only on if there is no pump signal. Therefore, when the optical output from the second semiconductor optical amplifier (SOA2; 152 ) is fed to the second optical filter, only the wavelength of the encoder signal is filtered, and this filtered signal is measured by the 45 GHz photodetector and the sampling oscilloscope.

4 shows the operating characteristics of a purely optical OR gate operating at 2.5 Gbit / s. The wavelength-converted signal pattern C shown in the upper position is a waveform which is formed when the two input signal patterns A (1100) and B (0110) are detected by the first semiconductor optical amplifier (SOA1; 140 ) are given. It is shown that there is no optical output for a logic signal of (1,0), (1,1) or (0,1) although the optical output is in the case of (0,0). The encoder signal shown at the lower position verifies that the operating characteristics of the all-optical OR gate are implemented when the drive currents of the second erbium-doped fiber amplifier (EDFA2; 144 ) and the second semiconductor optical amplifier (SOA2; 152 ) are each 170 mA and 150 mA.

As shown in the embodiment of the present invention, two input signal patterns A (1100) and B (0110) of the same wavelength are supplied to the first semiconductor optical amplifier (SOA1; 140 ) for providing the wavelength-converted signal pattern C having four logic signals (1,0), (1,1), (1,1) and (0,0), and when these logic signals and the encoder signal from the DFB-LD through the second semiconductor optical amplifier (SOA2; 152 ), a 2.5 Gbps all-optical OR gate is successfully executed based on the SOA characteristics of gain saturation and wavelength conversion. Therefore, using the present invention, all-optical logic operation can be easily performed in complicated optical circuits such as optical computing and all-optical signal processing systems.

As previously shown, according to the device, which for purely optical OR logic operations using an optical Semiconductor amplifier according to the present Invention is executed, the input signal of 2.5 Gbit / s to provide four logical signals through a mode locked fiber laser and multiplexing techniques used, and when these logic signals and the encoder signal through a semiconductor optical amplifier (SOA), the purely optical OR gate is characterized by the characteristics the gain saturation and wavelength conversion executed.

Therefore For example, the present invention is easy to perform the all-optical OR logic operation at any point of complicated optical circuits, such as optical computing and all-optical signal processing systems, be created. Also, the present invention can not only by running purely optical logic elements, such as purely optical NOR, NAND, XOR and AND gates, but also to form optical high-speed logic elements which are more than 10 Gbit / s are used.

Even though the present invention along with the accompanying drawings This only illustrates preferred embodiments, but does not limit the scope of the present invention. It is for the It will be apparent to those skilled in the art that various modifications be performed can, without the spirit and scope of the present invention, as he through the attached claims is defined, leave.

Claims (4)

Apparatus for purely optical OR logic operations comprising: an optical pulse generator; a mode-locked fiber laser (MLFL) for generating input signal patterns A and B for purely optical OR logic operations from the pulse generator; a first fiber coupler (FC1) for branching the output from the mode-locked fiber laser through a 50:50 branch ratio; a first optical delay means for delaying the optical output from the first fiber coupler; a first optical control means for controlling the intensity and the polarization of the optical output from the first fiber coupler; a second fiber coupler (FC2) for generating the input signal pattern A by coupling optical outputs from the first delay means and the first optical control means; a third fiber coupler (FC3) for branching the optical output from the second fiber coupler through a branch ratio of 10:90; second delay means for delaying the optical output from the second fiber coupler (FC2); a fourth fiber coupler (FC4) for detecting the optical output from the second delay means and measuring the input signal pattern B; second optical control means for controlling the intensity and the polarization of the optical output from the third fiber coupler (FC3); a fifth fiber coupler (FC5) for generating the input signal pattern A + B by coupling the input signal pattern A from the third fiber coupler and the input signal pattern B from the fourth fiber coupler; and means for detecting and measuring the input signal pattern A + B received from the fifth fiber coupler ( 130 ) is producible. Device for A purely optical OR logic operation according to claim 1, wherein modulated Waveforms from the mode-locked fiber laser (MLFL) at 2.5 Gbit / s are modulated, and the input signal pattern A of 1100 and the input signal pattern B of 0110 can be generated. An apparatus for a purely optical OR logic operation according to claim 1, further comprising: a first erbium-doped fiber amplifier (EDFA1) for amplifying the input signal pattern A + B which is producible by the fifth fiber coupler; a wavelength-adjustable laser diode ( 134 ) for providing a transmitter signal with a continuous wave; a sixth fiber coupler (FC6) for coupling the input signal pattern A + B for the first erbium-doped fiber amplifier and the continuous wave transmitter signal from the tunable laser diode through a coupling ratio of 50:50; a first semiconductor optical amplifier (SOA1) for generating the wavelength-converted signal pattern C by the SOA characteristics of the gain saturation and wavelength conversion from the input signal pattern A + B input from the sixth fiber coupler simultaneously with the encoder signal; and a first optical filter for filtering only the continuous wave transmitter signal from the first semiconductor optical amplifier. Device for a purely optical OR logic operation according to claim 3, additionally comprising: one second erbium doped fiber amplifier (EDFA2) for amplifying the Wavelength converted Signal pattern C from the first semiconductor optical amplifier; one Distributed feedback laser diode (DFB-LD) for generating optical Signals with continuous wave; a seventh fiber coupler (FC7) for coupling the signal pattern C which is doped at the second erbium fiber amplifier amplifiable and the continuous wave optical signal from the laser diode with distributed feedback through a coupling ratio from 50:50; a second semiconductor optical amplifier (SOA2) for Generating a new wavelength-converted Signal pattern by the SOA characteristics of the gain saturation and wavelength conversion, which is the wavelength conversion signal pattern C and the optical signal uses continuous wave, which simultaneously from the seventh fiber coupler as the pump signal, respectively and the encoder signal is input; and a second optical Filter for filtering only the encoder signal from the second optical Semiconductor amplifier.